The primary aims of this study are to ascertain the sensitivity, specificity, false positive and false negative rates of the combination of assessment of cervical length by cervical sonography, uterine contraction monitoring, vaginal fetal fibronectin, IL-6, matrix metalloproteinases (MMP-1, MMP-3, MMP-9), plasma estradiol and corticotropin-releasing hormone in predicting preterm labor. A secondary aim is to develop a demographic risk scoring system to predict preterm delivery risk and, if successful, to determine whether a patient's socioeconomic status and historical factors modify the predictive values of biochemical/physical factors in predicting preterm delivery. Blood will be banked on obstetrical patients and will be utilized for this study, SPID # 734 and #735. The lab will be used for blood separation and laminar flow hood use. Also, the core laboratory personnel are instrumental in teaching the investigators how to process and store patient samples. A data base for this study was set up by CDMAS. The GCRC statistician helped in the design of the study.